This is not "home" improvement per se, but it fits the spirit of this stack exchange. While waiting for my train I was peeking into a ceiling that had all of its slats removed for some kind of installation. I noticed there was a lot of new electrical conduit being laid which was made of copper. This struck me as really odd because this stuff is usually laid as aluminum or some kind of steel; copper is really expensive, it's not rust proof, nor is it electrically or thermally insulating, so I'm not understanding the choice in a more expensive material. The only answer I can possibly come up with it's better for its environment (moisture, against concrete; something re: anodization)

Bizarre to say the least. Maybe the foreman is banging for disability. It's also bizarre to see PVC used as a conduit for network cabling.
– mikeNov 4 '13 at 4:50

" it's not rust proof" ? Copper does not rust, it will oxidize and form a patina. Hundreds of millions of homes in America alone have copper WATER pipes precisely because it does not rust. As long as the water that it comes in contact with has a relatively neutral PH it will last for decades if not longer.
– Alaska ManSep 22 '17 at 18:07

4 Answers
4

I'm guessing it's plumbing, not conduit. Unless you actually see wires running through the tubing, I'm not convinced it's conduit. In the US only certain types of conduit are listed for use, and I'm sure they are similar in Canada. Copper is not among those listed, so it's not likely it would be approved by an inspector.

In a comment you mentioned that the pipe was connected using "nuts", and therefore could not be used for water. However, I disagree. A union is a fairly common fitting in plumbing. In fact, you'll probably find some if you look at the plumbing for the water heater in your house.

Article 344 Rigid Metal Conduit: Type RMC

II. Installation

(B) Corrosive Environments.(1) Galvanized Steel, Stainless Steel, and Red Brass
RMC, Elbows, Couplings, and Fittings. Galvanized steel,
stainless steel, and red brass RMC elbows, couplings, and
fittings shall be permitted to be installed in concrete, in
direct contact with the earth, or in areas subject to severe
corrosive influences where protected by corrosion protection
and judged suitable for the condition.

(C) Cinder Fill. Galvanized steel, stainless steel, and red
brass RMC shall be permitted to be installed in or under
cinder fill where subject to permanent moisture where protected
on all sides by a layer of noncinder concrete not less
than 50 mm (2 in.) thick; where the conduit is not less than
450 mm (18 in.) under the fill; or where protected by corrosion
protection and judged suitable for the condition.

Which means it's possible the conduit is not copper, but red brass. According to wikipedia, red brass may be 85% copper, 5% tin, 5% lead, and 5% zinc.

Alright, I took another look and it was definitely electrical. There were junction boxes branching off to the ceiling lights. Turns out it's original 60's era conduit and not new; just in good shape. Since then, buildings standards and material costs have changed drastically making it uneconomical to use.